/Engine/Source/Runtime/Engine/Classes/GameFramework/PlayerController.h
Forces the streaming system to disregard the normal logic for the specified duration and instead always load all mip-levels for all textures used by the specified material.
void ClientSetForceMipLevelsToBeResident ( class [UMaterialInterface](API\Runtime\Engine\Materials\UMaterialInterface) * Material, float ForceDuration, int32 CinematicTextureGroups )